Field of the Invention
The present invention relates to a technique for calculating a position and orientation of a measurement viewpoint on the basis of features extracted from measured data.
Description of the Related Art
Techniques that use features (natural feature points, markers, or the like) visible in an image, a range image, or the like obtained from a camera, a three-dimensional measuring sensor, or the like to calculate a position and orientation of the camera (a measurement viewpoint) are being widely used in self-localization for MR, AR, robots, and the like. Note that “MR” is an acronym for “Mixed Reality” while “AR” is an acronym for “Augmented Reality”. In such techniques, the accuracy at which the position and orientation of the camera (measurement viewpoint) are calculated varies depending on the arrangement of the features in a scene. It is necessary to adjust how a given feature pattern will be laid out in advance in order to calculate the position and orientation of the measurement viewpoint with the desired level of accuracy. Furthermore, to realize more convincing MR, it is necessary to ensure that the feature pattern that is laid out does not undermine the scenery.
Japanese Patent No. 4689380 (called “Patent Document 1” hereinafter) discloses a method, used in the case where the position and orientation of a camera is estimated using markers (printed products in which an identifier is coded as a predetermined geometric pattern) as features, for finding where the marker should be arranged in an environment. According to this method, region information pertaining to an accuracy at which a real space and a virtual space overlap is calculated on the basis of information of an index arranged in the real space; the region information is then visualized and displayed superimposed on the real space, which enables a user to find the arrangement of the marker in an interactive manner.
However, the method according to Patent Document 1 requires that a process of trial and error, in which the marker is arranged provisionally and the result thereof is then confirmed, be carried out repeatedly, and thus the task of laying out the feature (marker) takes time.